This invention relates to a mechanical heat transfer device and, more particularly, the invention is concerned with providing a unidirectional heat transfer device for an aircraft electronic assembly wherein a phase change heat absorbtion exchanger operates to transfer heat from the electronic assembly across the interface coupling surfaces to the aircraft skin until the skin reaches a predetermined elevated temperature at which time the interface surfaces are decoupled to prevent reverse heat flow back from the skin to the electronics.
There have been an increasing number of applications for cooling electronics aboard aircraft through the boundary layer skin heat transfer mode. This technique entails the establishment of a good thermal path for normal operation at moderate aircraft speeds and for decoupling this path during dash operation when skin temperatures are excessively high. As an example, at 20,000 feet, a fighter aircraft traveling at Mach number 0.9 will reach an adiabatic skin temperature of 101.degree. F.; at Mach 2.0, the skin reaches 375.degree. F. which is too high to be effective in electronic cooling.
The hereinafter described device provides a good thermal path from the electronics to the skin at normal aircraft speeds and at dash speeds imposes an interruption to heat conduction thus preventing heat flow from the skin to the electronics. By including a phase change heat absorption exchanger for the dash conditions, the maximum temperature of the electronics can be controlled within safe operating levels.